The invention relates to a piezoelectric igniter unit for a gas burner, particularly a gas fired barbecue grill.
More and more people are using gas fired barbecue grills, particularly as a result of their convenience. Such grills have an outer shell forming a firebox and cooking enclosure, with the gas burner being located at the inside of this shell adjacent its bottom. This is not a convenient location for access to ignite the gas by means of a match or the like and it is quite common for the manufacturer to incorporate a piezoelectric powered igniter apparatus which includes a pair of spaced electrodes adjacent the burner. When the piezoelectric generator is actuated, as by means of pressing a button or turning a handwheel, a spark is produced at the electrodes for the purpose of igniting gas emanating from the burner. It is common to locate the piezoelectric current generator at a location somewhat remote from the electrodes which are affixed in place adjacent the burner. A location for the current generator is selected such that it will be convenient to operate as the gas is turned on and the current generator is connected by suitable wires to the electrodes.
There are several disadvantages to such devices conventionally being used. Perhaps the most important is the deleterious effect caused by the heat of the gas flame during the time that it is burning for the purpose of barbecuing or other cooking. The electrodes, being necessarily immediately adjacent or even in the flame because of the necessity for their being at that location for the ignition of the gas, deteriorate comparatively rapidly. The relatively high temperatures to which they are subjected causes oxidation, etc., of the electrodes. Also, the part of the wiring adjacent its connection to the electrodes necessarily is in a location of relatively high heat, both as a result of radiation from the flame and as a result of the conduction of the heat through the electrodes to the wiring. Despite efforts to shield the wiring, it is quite difficult to prevent deterioration of the insulation about the wires.
Another disadvantage that is oftentimes present is the length of the wiring between the current generator and the electrodes. Piezoelectric generators of the type employed do not generate a great deal of electricity and the longer the wires between the generator and the electrodes the greater will be the electrical loss in those wires. The result can be that the amount of electricity available at the electrodes may be rather marginal from the standpoint of producing a spark which will be sure to ignite the gas. In a particular configuration of barbecue grill it may seem important to the manufacturer to mount the current generator at a particular location for convenience, but that location may be rather remote from the electrodes.
I have devised a piezoelectric igniter apparatus to overcome these problems without impairing the convenience of using the igniter apparatus. A push-button actuated piezoelectric current generator is mounted on a subframe with the push-button thereof extending outwardly away from the firebox housing and the electrodes on the other end of the subframe projecting toward the firebox housing. This subframe is movable along a path such that the electrodes project through an opening into the housing and are located adjacent the burner when a force is applied against the push-button in a direction such as to normally actuate it. When the subframe reaches this location and can move no farther, that force results in a depression of the button to cause the generation of electric current and thus a spark. Means are provided to urge the subframe in the opposite direction so that when the push-button is released that means causes a retraction motion of the subframe with the result that the electrodes are moved away from the position adjacent the burner and to a location at which they will be much less subjected to the heat of the burner. The piezoelectric unit and the wiring to the electrodes being on the subframe and completely outside of the firebox housing are not subjected to any significant radiant heat. Furthermore, the piezoelectric unit and the electrodes are relatively close together on the subframe with the result that the wiring therebetween is of a minimum length.
Further objects and advantages will be apparent from the following description taken in conjunction with the drawings.